Types and causes of contamination during operation of ultrapure water machines

     The laboratory water requirements are very high, and the ultrapure water mechanism is now commonly used to obtain the pure water and ultrapure water required for the experiment. During the operation of the ultrapure water machine, it is sometimes polluted, so how to identify the type and cause of pollution, let's talk about it in detail.

To identify the common pollution types of ultrapure water machines, it is necessary to comprehensively judge the raw water quality, design parameters, pollution index, operation records, equipment performance changes and microbial indicators:

1. Colloidal pollution: When colloidal pollution occurs, it is usually accompanied by the following two characteristics:

A. In the pretreatment, the microfilter is blocked very quickly, especially the pressure difference increases rapidly.

B. The SDI value is usually above 2.5.

2. Microbial contamination: When microbial contamination occurs, the total number of bacteria in the permeate water and concentrated water of the RO equipment is relatively high, and it must not be maintained and disinfected as required.

3. Calcium scale: It can be judged according to the raw water quality and design parameters. For carbonate type water, if the recovery rate is 75%, the scale inhibitor is added in the design, and the LSI of the concentrate should be less than 1; when no scale inhibitor is added, the LSI of the concentrate should be less than zero. Calcium scale will not be produced.

4. A 1/4 inch PVC plastic pipe can be inserted into the component to test the performance changes of different parts of the component.

5. Determine the type of pollution based on changes in equipment performance.

6. Pickling (such as citric acid, dilute HNO3) can be used, and the calcium scale can be judged according to the cleaning effect and the cleaning solution, and further confirmed by the composition analysis of the cleaning solution.

7. Chemical analysis of the cleaning solution: take raw water, cleaning stock solution, cleaning solution, and three samples for analysis. When the type of contamination cannot be determined, the steps of cleaning (3) + disinfection + 0.1% HCl (pH 3) are usually used.

The above are the common types and causes of pollution when the ultrapure water machine is running. Users need to understand these reasons in order to use the equipment better.